Apparatus for quenching workpieces



Sept. 29, .1970

Filed Aug. 14, 196

O. KRACH ETAL I APPARATUS FOR QUENCHING WORK'PIECES 2 Sheets-Sheet l INVENTORS Ottwz'n Krach Helmuzfh Lohse Karl Heinz Winter P 9, 1970 o. KRACH ETAL 3,531,096

APPARATUS FOR QUENCHING WORKPIECES I Filed Aug. 14, 1968 2 Sheets-Sheet :3

llrrn b} ca aaeeajaeeoea 1., H H, I rr\I INVENTORS Oztwz'n Krach fielmath Lohse Kar v lez'nz Winter United States Patent ()1 ice APPARATUS FOR QUENCHING WORKPIECES Ottwin Krach, Wolfgang, Helmuth Lohse, Frankfurt am Main, and Karl-Heinz Winter, Dornigheim, Germany, assiguors to Deutsche Golduud Silber-Scheideanstalt vormals Roessler, Frankfurt am Main, Germany Filed Aug. 14, 1968, Ser. No. 752,586

Claims priority, application Germany, Sept. 12, 1967,

Int. Cl. C21d 1/62 U.S. Cl. 266-6 4 Claims ABSTRACT OF THE DISCLOSURE Hot workpieces are dropped from an airtight furnace down through a shoot into a tank of aqueous quenching liquid. The shoot contains a layer of oil to prevent water vapor from the quenching liquid reaching the furnace. Battles in the shoot are used to trap any water vapor which may enter the oil layer.

This invention relates to an apparatus for quenching hot workpieces which are carburized, hardened, carbonitrated and austenized in furnaces having a protective gas and with the quenching taking place in water, aqueous solutions or other quenching media. Furnaces operating with a protective gas must be exceptionally well sealed in order to keep the consumption of protective gas at as low a level as possible and also, for example, during hardening and carburizing to maintain the required dew point. The furnace is sealed on the inlet side by gas curtains, locks, doors or other means and on the outlet side, in furnaces, for example, having reciprocating conveyors, by a discharge shoot submerged in the liquid quenching medium.

Furnaces are used in which the quenching medium consists of a known aqueous oil or a salt bath. In each of these cases, it is possible to produce a satisfactory seal without the risk that water vapor gets inside the furnace. However, quenching by oil or salt bath is not adequate for many types of steel. These steels have to be quenched in water, aqueous solutions or another quenching medium. In this case, however, it cannot be avoided that the furnace atmosphere becomes unusable by the water vapor produced during the quenching.

It is possible to cover the quenching medium, such as water, in the discharge shoot of the furnace with a layer of oil. When this is done, water bubbles are created when the red hot workpieces are submerged in the water bath. Water drops and vapor which move through the oil reach the interiorof the furnace.

The object of this invention is to produce an apparatus in which water vapor is prevented from moving through the oil in the discharge shoot.

In general, this object is obtained by mounting baflles in that part of the vertical or inclined discharge shoot containing the oil. Bubbles or water vapor condense on the bafiles. Water drop edges are provided on the bafiles for collecting the condensed water drops which then drip back into the quenching medium. By using such bafiles, the surprising result is obtained in that the interior of'the furnace remains completely free from water vapor despite the fact that the baflles are spaced from each other.

In this invention, it has been found desirable to recycle the oil in the shoot and return it to the shoot as one or more screening sprays above the surface of the oil. These screens assist in preventing the passage of all the vapors 3,531,096 Patented Sept. 29, 1970 produced in the quenching medium so that no vapors can adversely affect the interior of the furnace.

A further feature of this invention is to give the lower outlet portion of the shoot an enlarged funnel shape. By so doing, the oil which has been carried along with the workpieces going through the shoot is funneled upwardly into the shoot for further use.

The means by which the objects of this invention are obtained are described more fully with reference to the accompanying drawings in which:

FIG. 1 is a longitudinal cross-sectional view through the apparatus; and

FIG. 2 is an enlarged cross-sectional view through the shoot between the furnace and the quenching tank.

As shown in FIG. 1, the outlet end of furnace 1 is connected to a shoot 2 which goes into the quenching tank 3. Reciprocating conveyor 4 moves the hot workpieces 5, FIG. 2, through the furnace while being sealed off from air and the red hot workpieces are dropped through the shoot 2 into tank 3. In the tank the workpieces are moved by a conveyor belt or the like upwardly and are then discharged into a truck. The quenching liquid is water, aqueous solution or other quenching medium.

As shown in FIG. 2, the workpieces dropping through shoot 2 first fall through a spray or screening oil 6 and then into the layer of oil 7 in the shoot. This layer of oil floats on the quenching liquid 8 which enters the lower portion of the shoot. Mounted in shoot 2 are inclined bafiles 10 which are vertically spaced from each other and overlap. The undersides of these baflles have flanges 11 which form water drop edges. Water vapors entering the lower end of shoot 2 rise into the oil layer and are condensed on the baffles 10 so that the drops of water drip from the edges of the flanges 11 and fall back into the quenching medium. The baflles 10 are hollow and cooled by water. The bottom portion 12 of shaft 2 is conically enlarged in the form of a funnel. Oil which is carried along with the workpieces passing through the shoot is collected in this funnel-shaped lower portion 12 and rises back up into the oil layer 7.

The oil is recycled by pump P through pipe 14 back into tank 16 from which it is discharged in the form of the spray 6 above the layer of oil 7.

Having now described the means by which the objects of the invention are obtained,

We claim:

1. In an apparatus for the direct quenching of hot workpieces in a quenching medium such as water or aqueoussolutions comprising a furnace for the hardening, carburizing, carbo-nitrating or austenitizing of the workpieces in a controlled atmosphere, a quenching tank for containing the quenching medium, and an airtight shoot communicating between said furnace and said tank, the improvement comprising a non-aqueous liquid sealing layer means in said shoot for preventing the passage of water vapor from said quenching medium through said shoot, cooled baffle means in said sealing layer for condensing any water vapor coming from said quenching medium, and water drop edges on said baffle means for the collection and removal of water vapor condensate.

2. In an apparatus as in claim 1, further comprising means for injecting at least one cooling spray of a nonaqueous sealing liquid above said liquid sealing layer means.

3. In an apparatus as in claim 1, further comprising a funnel-shaped outlet end on said shoot opening into said quenching tank.

3 4 4. In an apparatus as in claim 1, said baffie means be- 3,441,452 4/1969 Western 148143 ing water cooled. 3,442,274 5/1969 Keough 266-4 References Cited UNITED STATES PATENTS GERALD A. DOST, Primary Examiner 1,086,621 2/1914 Rogers 266-6 5 us. 01. X.R. 2,063,784 12/1936 Bechtel et al 148143 3,340,109 9/1967 Keough 2664 134 105;148 143;2664 

